1. Field
The following description relates to an apparatus and a method of combining three-dimensional (3D) ultrasound images in order to obtain a combined 3D ultrasound image.
2. Description of Related Art
Ultrasound imaging is a technology related to transmitting inaudible high frequency sound waves having a frequency between 20 kHz and 150 MHz into an object and visualizing the internal structure of the object based on the waves reflected off from the internal structure of the object. Ultrasound image diagnosis techniques are classified into various modes according to how an image is displayed to the user. For example, brightness mode (B-mode) image diagnosis technique displays two-dimensional gray images that are used for general ultrasound diagnosis. Furthermore, an ultrasonic phased array transducer has two-dimensionally arranged elements that are lineally arranged therein for generating two-dimensional images; such an ultrasonic phased array transducer may steer or focus an ultrasonic beam. As a result, information regarding different section layers is obtained, and a three-dimensional image can be obtained by combining information regarding the different slices into one image. In addition, a real-time three-dimensional image (or four-dimensional image) may be realized, if the slices are combined substantially in real time.
However, due to a limited spatial range for capturing an ultrasound image, it is almost impossible to fully capture a Region of Interest (ROI) by one scan. For this reason, the same ROI is scanned at different locations, and a plurality of ultrasound images that partially overlap with each other are obtained. To put it simply, for accurate and thorough diagnosis on an ROI, a plurality of ultrasound images are analyzed, and the analyzing of each of the ultrasound images that belongs to the same ROI and the bringing about of an integrated and accurate diagnosis result therefrom are complicated and require expertise.
For example, a method for combining three-dimensional ultrasound images including a plurality of different special areas may involve comparing all or some of the pixels of a plurality of slices included in the three-dimensional ultrasound images with reference to locations and directions of the pixels. In this example, all the pixels/voxels of the three-dimensional images are compared with each other in order to combine the images; thus, a large amount of computation must be performed, requiring the use of a high-performance computing device and the consumption of a long processing time for performing the computation. Further, in an example in which a method for combining three-dimensional images by extracting characteristic shapes from the images and comparing the extracted shapes with each other is applied, there may be instances in which no characteristic shape, too few characteristic shapes or too many characteristic shapes are found; thus, the process of image combination may turn into a challenge. In yet another example, a method of combining three dimensional images using specific anatomical features (for example, blood vessel and bone) may be used for image combination. In this case, it is hard to interconnect three-dimensional images if an anatomical feature does not exist in each of the three-dimensional images that are being combined.